Method of preparing thiazoles



Patented Mar. 6, 1928.

UNIITEDOSTATES PATENT OFFICE.

' LORIN B. SEBRELL AND J'AN TEPPEMA, OF AKRON, OHIO, ASSIGNORS TO THE GOOD- 4 YEAR. TIRE & RUBBER COMPANY, OF AKRON, OHIO, A CORPORATION OF OHIO.

METHOD OF PREPARING THIAZOLES.

1T0 Drawing. Original application filed June 17, 1925, Serial No. 37,861.

Dividediand this application filed March 16, 1927. Serial No. 175,922.

Our invention relates to the preparation of mercaptothiazoles and it particularly pertains to that class of the above designated materials which embodies in its structure an 5 aryl-g'roup or substituted derivative thereof.

This application is a division of our copending application, Serial No. 37,861, filed June 17, 1925.

The object of this invention is to provide a new method of preparing mercaptothiazoles.

Briefly, the invention consists in reducin ortho-nitro-halide com ounds with a soluble basic hydro-sulfide sue for examples as the sodium pr ammonium derivatives in the presgrace of carbon bisulfide and hydrogen sule. Mercaptothiazoles and many of their derivatives are known to possess desirable 2 accelerating properties in the vulcanization of rubber. Many have been prepared and incorporated in caoutchouc mixes, chief among which may be mentioned 2-mercaptobenzothiazole, 2-mercapto-4-methyl-benzothiazole, Q-mercaptol-methylthiazole, 2-

mercaptoi-phenylthiazole, the structural formulas of which may be respectively designated as follows:

\MH 5 v 4 a I fi-Mereaptobenzothiazole 5 40 N on, v 3 2-Mercapto-4-methyI-benzoth1azole H o t OSH car- N 4 3 z-Meroaptwmethylthiazole H- O B 2 2-Mercapto'4-pheny1thiazole present method is characterized as one which utilizes cheap raw materials and requires little or no expensive equipment in securing the reaction. Moreover, a good yield may be had even when the'reaction is effected at relatively low temperatures, and in addition, a water solution. may be employed thereby obviating the necessity of costly solvents.

- The preparation of 2-mercaptobenzothiazole may be taken as characteristic, for purposes of illustrating the application of the principles of our invention. One hundred parts of. ortho-nitro-chlorbenzene are sus pended in a water solution of two hundred fifty parts of sodium sulfide, previously saturated with hydrogen sulfide. The mixture is warmed slightly and hydrogen sulfide, which is saturated with carbon bisulfide, is passed through the solution. We have found that a ninety percent yield is obtained when the reaction is carried out at atmospheric pressure and between and 90 C. In order to reduce the time of reaction, however, a positive pressure of the gaseous materials which may aggregate 250 pounds per square inch and an elevated temperature which even exceeds 150 C. may be employed. In the latter case, the yield is somewhat impaired although the time necessary to complete the reaction is materially reduced. Subsequently the reacted'mixture is steam distilled to remove undesirable by-products. or raw materials, after which the charge is acidified. The precipitated product thus ble basic sulfide, or h drosulfide will sufiice. The reaction is proba ly as follows:

+ NaSH c1 SH O-amlno-thiophenol N ban ms Many modifications of this invention will 0 be readil apparent. For example, diorthodinitro-dlphenyl-disulfide, which itself may be easily prepared from ortho-nitro-chlorbenzene by reacting with sodium polysulfide, is a convenient starting material.v Thus, if

' s s n N0 NH1 1 B CS NH: u

2-memptobenzothlazole to hexa-cyclic structures but contemplate both open chain and rin structures which are so characterized. erha s the best known examples are the ort o-nitro-aryl halides. I

Although we have disclosed but a single embodiment of the principles of our invention, together with a slight modification thereof, it will be appreciated by anyone skilled in the art that they may be extended to a large class of materials which are known to react in a manner analo ous to the phenyl compound and that any 0% the intermediate pro ucts desi ated in the above reactions ma be substltuted for the original materia Furthermore, while a set of reacting conditions have been specifically set forth, it is obvious that they are merely exemplary five parts of the disulfide be suspended in one hundred parts of water, to which 1s added an equivalent quantity of a solution of sodium sulfide, that has previously been saturated with hydrosulfide and subsequently hydrogen sulfide that has been treated with carbon bisulfide is bubbled through the mixture, which is maintained at substantially 50 0., a theoretical yield of the 2-mercaptobenzothiazole is obtained in about five hours. The steps involved in its urification need not again be discusse This alternative method comes clearly within the provisions of the present invention as will be readily appreciated by comparing the reactions involved.

dlortho-dlnitrodlphenjl-dlsulflde 14 NeHS---o7 NmS +14 H +7 5 and that many variations may be made without departing from the scope of the invention. We desire, therefore, that only such limitations shall be imposed as are consistent with the prior art and the appended claims.

What we claim is:

1. A method of preparing a mercaptoaryl-thiazole, that comprises causing the corresponding diortho-dinitro-diaryl-disulfide to react with an alkaline h drosulfide in the presence of carbon bisulfi e.

2. A method of preparing a mercaptoaryl-thiazole, that comprises causin the corresponding diortho-dinitro-diary -disulfide to react under the influence of positive pressure and elevated tem erature with an alkaline hydrosulfide in t e presence of carbon bisulfide.

3. A method of preparing mercaptobenzothiazole, that comprises causing the correrespondin diortho-dinitro-diar l-disulfide to react wlth an alkaline hydrosu fide in the presence of carbon bisulfide.

4. A method of manufacturing Q-mercaptobenzothiazole which comprises, causing diortho-dinitro-diphenyl-disulfide to react with a water solution of a basic sulfide in the presence of hydrogen sulfide and carbon bisulfide.

In witness whereof, we have hereunto signed our names in the presence of two subscribing witnesses.

' LORIN B. SEBRELL.

JAN TEPPEMA. 

